Refactoring itk::FEM framework - V4

This page outlines the proposed changes to the itk::FEM framework. Feed back on these changes should be sent to Vincent Magnotta (vincent-magnotta - at- uiowa.edu). A number of these changes will break backwards compatibility.

Changes to the FEM Framework Classes

itk::Solver

1. Move the following class variables from public to protected:
   • node
   • el
   • load
   • mat
2. Add the following member functions:
   • bool AddNextElement(ElementType *element) – Add the next element to the mesh data structure. This will be used to replace the solver->el.push_back()
   • bool InsertElement(ElementType *element, unsigned long index) – Insert the element to the position within the mesh data structure.
   • bool AddNextNode(NodeType *node) – Add the next node to the mesh data structure. This will be used to replace the solver->node.push_back()
   • bool InsertNode(NodeType *node, unsigned long index) – Insert the node into the desired location within the mesh data structure.
   • bool AddNextMaterial(itk::fem::FEMP<itk::fem::Material>) – Add the next material type to the solver.
   • bool InsertMaterial(itk::fem::FEMP<itk::fem::Material>, int) – Insert the material property to the specified index in the solver material property array.
   • bool AddNextLoad(itk::fem::FEMP<itk::fem::Load>) – Add the next load to the solver.
   • bool InsertLoad(itk::fem::FEMP<itk::fem::Load>, int) – Insert the load to the specified index in the solver load array.
   • bool GetElement(unsigned long index, ElementType *element) – Get the specified element from the mesh data structure
   • bool GetNode(unsigned long index, NodeType *node) – Get the specified node from the mesh data structure
   • bool GetMaterial(itk::fem::FEMP<itk::fem::Material>, int) – Get the specified material from the solver.
   • bool GetLoad(itk::fem::FEMP<itk::fem::Load>, int) – Get the specified load from the solver.
   • unsigned int GetNumberOfNodes() – Returns the number of nodes stored in the solver.
   • unsigned int GetNumberOfElements()– Returns the number of element stored in the solver.
   • unsigned int GetNumberOfMaterials()– Returns the number of materials stored in the solver.
   • unsigned int GetNumberOfLoads() – Returns the number of loads stored in the solver
   • bool ClearMaterialArray() – Insert the load to the specified index in the solver load array.
   • bool ClearloadArray() – Insert the load to the specified index in the solver load array.
   • bool RemoveMaterial(int) – Remove the material property at the specified index from the solver Material array.
   • bool RemoveLoad(int) – Remove the load at the specified index from the solver load array.
   • void SetMesh(itk::Mesh) – Specify the entire mesh to be used by the solver.
   • itk::Mesh GetMesh() – Returns the mesh used by the solver.
   • MeshType::Pointer GetDeformedMesh() – Returns the resulting mesh after applying the loading and boundary conditions on the mesh.
   • itk::Array<double>::Pointer GetMeshStresses() – Returns the stresses for the mesh with each element of the array corresponding to an element in the mesh.
   • itk::Array<double>::Pointer GetMeshStrains()– Returns the strains for the mesh with each element of the array corresponding to an element in the mesh.

itk::fem::Load

itk::fem::LightObject

1. Move the following class variables from public to protected:
   • GN
2. Add public methods to get/set the class variables
   • void SetGlobalNumber(int) – Set the global number for the FEM object. The default value is -1.
   • int GetGlobalNumber() – Get the global number for the FEM object.

itk::fem::LoadBC

1. Move the following class variables from public to protected:
   • m_dof
   • m_element
   • m_value
   • CLID
2. The following class functions will be added, allowing the user to get and set the class variables:
   • void SetDegreesOfFreedom(unsigned int dof) – Set the degrees of freedom for the local element for which the boundary condition is being applied.
   • void SetElement(Element::ConstPointer element) – Set the element for which the boundary condition is being applied.
   • void SetValue(vnl_vector< Element::Float > value) – Set the boundary condition using a vector representation. This can be used to restrict motion of an element in a particular direction.
   • unsigned int GetDegreesOfFreedom() – Returns the local degrees of freedom for the element on which the boundary condition is being applied.
   • Element::ConstPointer GetElement() – Returns the element on which the boundary condition is being applied.
   • vnl_vector< Element::Float > GetValue() – Returns the assigned boundary condition.

itk::fem::LoadBCMFC

1. Move the following member variables from public to protected:
   • Index
   • lhs
   • rhs
2. Add class methods to get and set the class variables.
   • void SetIndex(int) – Set the index variable for the multi freedom displacement constraint. This is used internally by the itk::Fem::Solver.
   • void AddLeftHandSideTerm(LoadBCMFC::MFCTerm) – Add terms to the right hand side of the multi freedom displacement constraint. Used to replace loadBCMFC.lhs.push_back().
   • void AddRightHandSideTerm(vnl_vector< Element::Float >) – Set the right hand side of the linear equation that defines the constraints. Replaces loadBCMFC.rhs = a;
   • int GetIndex – Get the index variable for the multi freedom displacement constraint.
   • int GetNumberOfLeftHandSideTerms() – Returns the number of terms used to define the left hand side of the multi freedom displacement constraint.
   • itk::LoadBFMC GetLeftHandSideTerm(int index) – Returns the specified left hand side term.
   • int GetNumberOfRightHandSideTerms()– Returns the number of terms used to define the left hand side of the multi freedom displacement constraint.
   • Element::Float GetRightHandSideTerm(int index) – Returns the specified right hand side term.

itk::fem::LoadEdge

1. Move the following member variables from public to protected signatures:
   • m_Edge
   • m_Force
2. Provide public interface to get/set class variables
   • void SetEdge(int) – Set the edge to apply the desired force.
   • void SetForce(vnl_matrix< Float >) – Set the force to be applied to an edge.
   • int GetEdge() – Get the edge for the applied force.
   • vnl_matrix< Float > GetForce() – Get the force applied.

itk::fem::LoadGravConst

1. Move the following class variables from public to protected signatures.
   • Fg_value
2. Provide class methods to get/set the class variables
   • void SetForce(vnl_vector< Float >) – Set the constant force vector that exists for every point in space.
   • vnl_vector< Float > GetForce() – Return the constant force vector that exists for every point in space.

itk::fem::LoadLandmark

1. Move the following class variables from public to protected signatures.
   • eta
   • m_force
   • m_pt
   • m_Solution
   • m_Source
   • m_Target
2. Add the following public interface
   • void SetEta(double) – Set the square root of the variance.
   • double GetEta(double) – Get the square root of the variance.

itk::fem::LoadNode

1. Move the following class variables from public to protected signatures:
   • F
   • m_element
   • m_pt
2. Add the following class member functions
   • void SetForce(vnl_vector< Float >) – Set the applied force to the node.
   • void SetElement(Element::ConstPointer) – Set the element in the system that contains the degrees of freedom on which the force is applied.
   • void SetNode(unsigned int) – Set the point on which the force is being applied.
   • vnl_vector< Float > &GetForce() – Get the applied force.
   • Element::ConstPointer GetElement() – Get the element in the system that contains the degrees of freedom on which the force is applied.
   • Unsigned int GetNode() – Get the point on which the force is being applied.

itk::fem::LoadPoint

1. Move the following class variables from public to protected signatures:
   • Fp
   • point
2. Add public class methods to access these variables:
   • void SetForce(vnl_vector<Float>) – Set the force to be applied to the specified point location.
   • void SetPoint(vnl_vector<Float>) – Set the point where the force is applied in global coordinates.
   • vnl_vector<Float> & GetForce(vnl_vector<Float>) – Get the applied force.
   • vnl_vector<Float> & GetPoint (vnl_vector<Float>) – Get the point where the force is applied.